1. Field of the Invention
The present invention relates to a gas turbine and a method of cooling the high temperature section of gas turbine.
2. Description of Prior Arts
To meet growing demands for electric power in recent years and to combat global warming, it is necessary to increase the capacity and enhance efficiency of gas turbine power generation facilities. Especially in gas turbine power generation facilities where fuels are supplied and burnt with air compressed by a compressor and fed to the combustor and the gas turbine is driven by this combustion gas, large capacity and high efficiency can be achieved by further increasing fuel temperature. In this case, however, the gas turbine for collecting energy of the combustion gas exposed to high temperature will be damaged and a serious accident may occur if it is not cooled. So in gas turbine power generation facilities where combustion gas temperature is high, compressed air and steam are used to cool the high temperature section of gas turbines.
With consideration given to possible pressure loss in the flow path of cooling air, high-pressure air is used as cooling air for cooling the high temperature section of a turbine.
In an open cooling gas turbine where cooling air is discharged into the turbine gas path, air extracted from the low-temperature compressor is directly used as cooling air. Air discharged from the compressor is cooled by a cooler, and is used to cool high temperature sections.
In a closed cooling type gas turbine where cooling air used to cool the high temperature section of the turbine is collected into the combustor and is used as combustion air, there is pressure loss of cooling air in the flow path of the turbine high temperature section. So in order to collect cooling air into the combustor, the pressure of air discharged from the compressor must be increased by a boost compressor. If it is increased by the boost compressor, cooling air temperature will rise. This requires installation of a cooler which adjusts the cooling air temperature to an appropriate level.
For example, JP A No. 10-196316 discloses a system configuration where air discharged from the compressor is cooled by heat exchanger to cool the high temperature section of a turbine.